Glow discharge oscillator



July 25, 1939. E BAUER 2,167,496

@Low DISCHARGE oscILLAToR Filed oct. 2o, 193e Y @CW Patented July 25, 1939 UNITED STATES PATENT orFicE GLOW DISCHARGE OSCILLATOR Erwin Bauer, Mannheim, Germany, assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany, a company 4 Claims.

The invention has for its object to render the frequency of a glow discharge oscillator independent of variations in the working conditions. If, for instance, the supply voltage is varying, then with a glow discharge oscillator of the customary type the frequency too is subject to variations. The supply voltage, it is true, may be kept constant with the aid of a glow voltage divider. .'Since, however, such glow voltage dividers take some time to attain their full efficiency, the frequency will only be constant after a certain duration. The invention fulfills the problem of obtaining a constant frequency immediately after the apparatus has been cut in.

This is attained by conducting to the discharge circuit of the glow tube a voltage derived from the oscillator frequency and by which frequency variations are counteracted.

One embodiment of the invention is described hereinafter, reference being had to the accompanying drawing in which Fig. 1 is a wiring diagram of the arrangement chosen as an example,

Figs. 2 and 3 are diagrams relating to the mode of action thereof.

The condenser Cl is charged over resistance IRI until the ignition voltage of the glow tube GI, included in the grid circuit of the tube R, is attained. Condenser CI then discharges over tube Gl and the secondary of the transformer T2 till .the extinction voltage of GI is attained. This :action will periodically recur. Due to the con.- denser-resistance coupling C2, R4 the tube R is controlled by the respective relaxation Voltage, that is, by oscillations whose graphic representation is saw-tooth shaped in a well known manner.

The arrangement as thus far described is well known. If, as shown in Fig. 2, the supply voltage V decreases to the value V then the ignition delay interval (i. e. the condenser charging time) will be longer. In Fig. 2 VZ denotes the ignition voltage while VL denotes the extinction voltage. It will be readily seen that the ignition delay interval t2 pertaining to voltage V is longer than the ignition delay interval tl, which corresponds to the voltage V. As a result, a decrease in frequency would occur.

In accordance with the invention there is included in the output circuit of the tube R, Fig. 1, a transformer TI which acts over resistance R2 to connect a predetermined amplitude to the primary of transformer T2 arranged in the discharge circuit of the glow tube Gl. This amplitude is contrary to the oscillation in the discharge (Cl. Z50-36) circuit Cl, Gl and thus acts to dirninsh the voltage applied across the glow tube by a predetermined amount. If now voltage V decreases then the amplitude taken from the output circuit of the tube R becomes smaller. In the discharge 5 circuit Cl, Gl therefore the voltage applied across the tube is increased in accordance with the decrease of the amplitude in the anode circuit, that is to say, in this circuit CI, Gl an increase in frequency occurs. From Fig. 3 it will 10 appear how the amplitude of output from tube R varies in the event of the supply voltage V decreasing. On the characteristic line I, which is given by the desired voltage VI, the working point is with the aid of resistances R3, R4 so ad- 15 `iusted that the operation takes place on the straight part of the characteristic line. On decrease of the supply voltage to the value VII the operation is based on the characteristic line II. The control voltage thus produces oscillations in the anode circuit Whose amplitudes correspond to the value JII. These however are smaller in accordance with the diminution of V. By adjusting Rl, R2, R3, Fig. 1, it is possible to attain that the decrease in frequency appearing from Fig. 2 25 shall be compensated by the described increase in frequency due to decreasing the amplitude in the anode circuit of tube R. In this way, whenever the oscillator is cut in a constant frequency is obtained immediately, this frequency being independent of the variation of the voltage V.

If the apparatus is supplied by a mains device used for heating the tube R, then also the Variations in the heating voltage also may be largely compensated in the described manner.

The glow lamp G2, Fig. 1, serves to stabilize the grid bias of the tube R, this bias being adjusted by means of the resistances R3, R4.

What is claimed is:

1. A glow discharge oscillator adapted to generate oscillations and comprising a glow tube, a source of variable voltage applied thereto and a discharge circuit therefor, means for deriving an alternating voltage from said oscillations and for applying this alternating voltage to said discharge circuit for counteracting the variations of voltage applied to said glow tube from said source, and means included in said first mentioned means and variably responsive to changes in the voltage of said source to cause such alternating voltage to vary, the variations in said alternating voltage being of such value as to counteract frequency variations of said oscillator in responseto said voltage changes.

2. A glow discharge oscillator according to claim 1, wherein the means for deriving and applying the alternating voltage are adapted to apply the said alternating voltage 180 out of phase with respect to the oscillations in said discharge circuit.

3. A frequency stabilized oscillation-generating system comprising a glow tube, a voltage source, a condenser-resistor circuit, connections for applying to said glow tube iiuctuating voltage from said source at a rate controlled by said circuit to cause ignition and extinction of said glow tube whereby periodic relaxation oscillations are generated, means for deriving from said oscillations an alternating voltage variable in response to fluctuations in voltage of said source, means for applying said variable alternating voltage to said glow tube while said tube is in extinguished condition in such phase and amplitude that the variation of said alternating voltage responsive to a given fluctuation in voltage of said source causes a change in ignition delay of said glow tube of substantially the same amount as but in the opposite sense from the change in ignition delay caused by the said given fluctuation itself.

4. A frequency stabilized oscillation-generating system comprising a glow tube, a fluctuating Voltage source, a condenser-resistor circuit, connections for applying to said glow tube voltage from said source at a rate controlled by said circuit to cause ignition and extinction of said glow tube whereby periodic relaxation oscillations are generated, means for deriving from said oscillations an alternating voltage variable in response to fluctuations in voltage of said source, means variably responsive to fluctuations in voltage of Said source for further varying said alternating voltage in response to said fluctuations, means for applying said further Varied alternating Voltage to said glow tube while said tube is in extinguished condition in such phase and amplitude that the variation of said alternating voltage responsive to a given fluctuation in voltage of said source causes a change in ignition delay of said glow tube of substantially the same amount as but in the opposite sense from the change in ignition delay caused by the said given iiuctuation itself.

ERWIN BAUER. 

